Magnetic hysteresis and rotational energy barriers in C-coated Co and RE/TM fine particle ferromagnets

We use a Kratschmer-Huffman C-arc method to synthesize C-coated transition metal (TM) and rare earth (RE)-TM nanocrystals. The theme of this research is C-arc synthesis of magnetic materials and assessment of potential use in xerography, ferrofluids, data storage, MRI image enhancement, etc. Here we focus on materials with potential for data storage, TM particles include Co[C]. Sm/sub 1-x-y/Co/sub x/C/sub y/ nanocrystals have been produced using a Sm/sub 2/Co/sub 7/ precursor, as have nanocrystalline Fe/sub 1-x-y-z/Nd/sub x/B/sub y/C/sub z/ using Fe/sub 14/Nd/sub 2/B. Characterization by XRD and HRTEM identify phases and particle sizes. SQUID magnetometry is used to determine magnetic hysteresis, temperature, and time dependent response.